Fair Value of Financial Instruments - Assets measured on a recurring basis (Details) - Fair Value, measurements, recurring - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Other Trading Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year		$ 859	$ 1,117
Total gains or losses (realized/unrealized):
Included in earnings	[1]	(40)	(46)
Purchases, issuances, sales and settlements:
Balance, end of year		819	1,071
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held		(40)	(46)
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year		293	253
Purchases, issuances, sales and settlements:
Purchases		4
Sales		0	0
Balance, end of year		297	253
Interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year		2,392	2,874
Total gains or losses (realized/unrealized):
Included in earnings	[1]	785	822
Purchases, issuances, sales and settlements:
Balance, end of year		3,177	3,696
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held		785	822
Other assets - MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year		51,428	44,541
Total gains or losses (realized/unrealized):
Included in earnings	[1]	(2,670)	(8,231)
Included in other comprehensive income		0
Purchases, issuances, sales and settlements:
Purchases		0
Issuances		2,018	4,407
Balance, end of year		50,776	40,717
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held		(2,670)	$ (8,231)
Other assets - SBIC investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year		15,639
Total gains or losses (realized/unrealized):
Included in earnings		550
Purchases, issuances, sales and settlements:
Purchases		6,364
Balance, end of year		22,553
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held		$ 550

[1] Included in noninterest income in the Unaudited Condensed Consolidated Statements of Income.